JPH08339550A - Adjusting method for control circuit for optical disk driving device - Google Patents

Abstract

PURPOSE: To enable a control circuit to perform a stable tracking control by performing focus adjustment for maximizing the amplitude of information signal before performing the offset adjustment of tracking error signal and the tracking servo pull-in. CONSTITUTION: Before performing tracking pull-in after performing focus pull-in by a servo part 8, A control part 9 adds an electric offset voltage to a focusing error signal detected during the movement of an objective lens and performs defocusing adjustment so that the amplitude of an information signal is made to be maximum. In an optical disk driving device 1 using an optical pickup 4 generating a tracking error signal by a pushpull system, by this adjustment, even when the pit shape of an optical disk 2 is asymmetric and the irradiating angle with a light beam is not perpendicular to the disk 2, a tracking error signal is adjusted by completely canceling the offset and stable tracking control is made possible while keeping a necessary jitter level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of adjusting a control circuit for an optical disk drive device which enables stable tracking.

[0002]

2. Description of the Related Art In recent years, an optical disk drive apparatus is an apparatus for narrowing the light emitted from a light source such as a semiconductor laser onto an optical disk surface by an objective lens through an optical prism or the like to record / reproduce a signal on a track. Not only for music playback, but also for information recording / playback.

By the way, optical pickups for detecting data recorded as pits on a disc in an optical disc drive apparatus are classified into several types according to a detection system of reflected light.

In particular, regarding the detection of the tracking error signal, two types are well known: a push-pull method using one light beam (one-beam method) and a three-beam method using three light beams.

The control method of the optical pickup of the conventional optical disk drive will be described below. FIG. 3 is a flowchart showing a conventional method of adjusting the control circuit for an optical disk drive device.

First, when an optical disk reproduction command is issued, the control circuit causes the laser diode of the optical pickup to emit light, and then drives the focus actuator to move the objective lens within a predetermined movement range (step 1). The moving range of the objective lens is preset so that the objective lens position corresponding to the focal point of the light beam exists within the moving range.

In parallel with this, the control circuit performs focus pull-in (step 2). More specifically, the focus error signal detected during movement of the objective lens is monitored to detect whether or not the objective lens has reached the position corresponding to the in-focus point. When it reaches, the closed loop control mode is entered by using the focus error signal as a control signal.

Then, the spindle motor is started, and the rough CLV whose linear velocity adjustment permissible range is slightly wider than that during normal reproduction.
When the mode is entered, offset adjustment is performed so that the center of the tracking error signal amplitude matches the servo reference voltage level (step 3).

Next, tracking pull-in is performed (step 4). When tracking pull-in is performed, defocus adjustment is performed to maximize the jitter best point or the information signal amplitude (step 5).

After the defocus adjustment, the AGC that makes the gains of the focus servo and the tracking servo optimal values
(Auto gain control) is performed (step 6), and data reading is performed (step 7).

[0011]

However, in the conventional method of adjusting the control circuit for the optical disk drive device, when the pit shape of the disk is asymmetric or the irradiation angle of the light beam is not perpendicular to the disk, The defocus adjustment causes an offset in the tracking error signal in the push-pull method. Due to this offset, the spot of the light beam deviates from the center of the track to be servo-operated, so that there are problems that the track is easily deviated and jitter is deteriorated.

At this point, if the adjustment is performed again so as to cancel the offset of the tracking error signal, the defocus position deviates from the best jitter point, and the adjustment does not converge.

Therefore, an object of the present invention is to provide an adjusting method of a control circuit for an optical disk drive device which can perform stable tracking control while ensuring a required jitter level.

[0014]

According to the present invention, after focus pull-in is performed by the focus servo means,
Before performing tracking pull-in by the tracking servo means, defocus adjustment is performed so that the information signal amplitude becomes maximum.

[0015]

According to the above construction, the offset occurring in the tracking error signal can be canceled, so that the tracking control can be stabilized while ensuring the required jitter level.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an optical disk drive device according to an embodiment of the present invention. In FIG.
The optical disk drive device 1 includes a spindle motor 3 that rotates an optical disk 2, a pickup 4 that outputs recorded information of the rotating optical disk 2 as a read information signal (RF signal), and an RF signal that is amplified to form an RF amplified signal. The RF amplifier unit 5 for outputting and the RF amplified signal are converted into a binary signal and the frame synchronization pattern is separated.
A decoder unit 6 that performs FM demodulation, performs signal processing such as error correction, and outputs as reproduction data, and an interface unit 7 that performs an interface operation between the reproduction data output by the decoder unit 6 and an external host computer or the like. , A servo unit 8 that performs focus servo, tracking servo, carriage servo, and spindle servo based on the output signals of the RF amplifier unit 5 and the decoder unit 6.
A control unit 9 that controls the entire optical disc drive device 1 and a display operation unit 10 that inputs and displays various data under the control of the control unit 9.

Next, the operation during reproduction in the optical disk drive device 1 will be described with reference to FIG.

FIG. 2 is a flow chart showing a method of adjusting the control circuit for the optical disk drive device according to the embodiment of the present invention.

First, when a command for reproducing the optical disk 2 is issued through the display / operation unit 10, the control unit 9 causes a laser diode provided in the pickup 4 to emit light, and then drives a focus actuator (not shown). , The objective lens to the information recording surface of the optical disc 2,
It is moved vertically within a predetermined distance range (step 1). Here, it is assumed that the focus actuator is adjusted in advance so that the focus of the light beam is within the range in which the objective lens moves.

In parallel with this, the control section 9 monitors the focus error signal detected during the movement of the objective lens, and when it detects that the in-focus point is reached based on the output signal of a photodetector (not shown), the focus error signal is detected. Is entered as a control signal (step 2).

Next, the control unit 9 drives the spindle motor 3 via the servo unit 8 and starts the operation to enter the rough CLV mode. What is this rough CLV mode?
The linear velocity is not made constant as in normal reproduction, but the rotational velocity of the optical disc 2 is pulled into a certain linear velocity range.

When the rough CLV mode is set, first, defocus adjustment is performed (step 3). The defocus adjustment is to add an offset voltage to the focus error signal so that the peak value of the RF signal amplitude becomes maximum.

Instead of monitoring the peak value of the RF signal amplitude, an average value obtained by integrating the RF signal amplitude may be monitored.

Next, the offset of the tracking error signal is adjusted (step 4). Then, after the defocus adjustment and the offset adjustment of the tracking error signal are completed, the tracking servo pull-in is performed (step 5).

When the tracking servo pull-in is completed, the control section 9 carries out the AGC of the focus servo and the tracking servo (step 6).

As a result, the pickup 4 starts reading the recorded information on the optical disc 2 and outputs the RF signal as an RF signal.
The RF signal is output to the amplifier unit 5, and the RF amplifier unit 5 receives the input RF signal.
The signal is amplified and output to the decoder unit 6 as an RF amplified signal.

As a result, the decoder unit 6 converts the RF amplified signal into a binary signal, separates the frame synchronization pattern, performs EFM demodulation, performs signal processing such as error correction, and reproduces it via the interface unit 7. The data is output to an external host computer or the like (step 7).

As described above, according to the present embodiment, before the offset adjustment of the tracking error signal and the tracking servo pull-in are performed, the defocus adjustment for maximizing the RF signal amplitude is performed. In an optical disc drive device using an optical pickup that generates a signal, even if the pit shape of the disc is asymmetric or the irradiation angle of the light beam is not perpendicular to the disc, the offset of the tracking error signal can be completely canceled and adjusted. Therefore, stable tracking control can be performed.

[0030]

According to the present invention, since the defocus adjustment for maximizing the RF signal amplitude is performed before the offset adjustment of the tracking error signal and the tracking servo pull-in, the tracking error signal is generated by the push-pull method. In an optical disk drive device using an optical pickup, stable tracking control can be performed even when the pit shape of the disk is asymmetric and the irradiation angle of the light beam is not perpendicular to the disk.

[Brief description of drawings]

FIG. 1 is a block diagram of an optical disk drive device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an adjusting method of a control circuit for an optical disk drive device according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a conventional method for adjusting a control circuit for an optical disk drive device.

[Explanation of symbols]

 1 optical disk drive device 2 optical disk 3 spindle motor 4 pickup 5 RF amplifier section 6 decoder section 7 interface section 8 servo section 9 control section 10 display operation section

Claims (1)

[Claims] 1. An optical disc drive apparatus, wherein after adding focus by a focus servo means and before performing tracking draw by a tracking servo means, an electrical offset voltage is added to a focus error signal, A method of adjusting a control circuit for an optical disk drive device, which comprises performing defocus adjustment so that an information signal amplitude becomes maximum.